US president also says delayed tariffs on imports from Canada and Mexico will go into effect on 4 March

Donald Trump has threatened China with an additional 10% tariff on its exports to the US, prompting a promise of “countermeasures” from Beijing and setting the stage for another significant escalation in the two governments’ trade war.

The US president also claimed he planned to impose tariffs on Canada and Mexico starting next Tuesday, having delayed their imposition last month following talks with his counterparts.